Exposure to ionizing radiation modifies neurally-evoked electrolyte transport and some inflammatory responses in rat colon in vitro.
OBJECTIVE
To characterize the responsiveness of the colon to neural stimulation following acute exposure of rats to gamma-radiation and to correlate observed changes to a number of parameters.


METHODS
Rats were exposed to 5 or 10 Gy 137Cs gamma-radiation or not (sham-irradiated) and studied at 1, 3 and 7 days after irradiation. Stripped segments of colon were mounted in Ussing chambers for measurements of neurally-evoked electrolyte transport (electrical field stimulation). Colonic tissue was also taken for biochemical (tissue 5-hydroxytryptamine, histamine, leukotriene B4, nitric oxide synthase) and histological analyses (mast cells).


RESULTS
In irradiated rats both proximal and distal colon were hyporesponsive to electrical field stimulation at 1 and 3 days, but had recovered by 7 days. In the distal colon, carbachol responses were attenuated 1 day after 10 Gy. Mast cells, tissue histamine and leukotriene B4 synthesis were significantly reduced at all time points but no changes were seen in 5-HT or inducible NOS activity.


CONCLUSIONS
Rat colon becomes hyporesponsive to neural stimuli post-irradiation. The response initially (1 and 3 days) correlates with decreased mast cells and histamine, but not at 7 days.
François
A
A
Institut de Protection et de Sûreté Nucléaire, Département de Protection de la Santé de l'Homme et de Dosimétrie, IPSN, FONTENAY-aux-ROSES, France.
Aigueperse
J
J
Gourmelon
P
P
MacNaughton
W K
WK
Griffiths
N M
NM
D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D003106:Colon / Q000378:metabolism / Q000528:radiation effects*; D004558:Electric Stimulation; D004573:Electrolytes / Q000378:metabolism*; D017136:Ion Transport; D007975:Leukotriene B4 / Q000032:analysis; D008297:Male; D008407:Mast Cells / Q000528:radiation effects; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000032:analysis
D004573:Electrolytes; D007975:Leukotriene B4; D012701:Serotonin; D002217:Carbachol; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat